Gadolinium-activated phosphate phosphor

Abstract

A gadolinium-activated phosphate phosphor expressed by the general chemical formula: (R1-x-yGdxMy)3(PO4)(2+x-y)z where R denotes calcium, zinc, strontium, barium, or magnesium; M represents thallium, silver, lithium, barium, sodium, potassium, rubidium or cesium; 0.005</=x</=0.35; 0</=y</=0.3; and 0.7</=z</=1.9.

What we claim is: 
     
       1. A gadolinium-activated calcium phosphate phosphor of the formula:   (Ca.sub.1-x-y Gd.sub.x M.sub.y).sub.3 (PO.sub.4).sub.(2+x-y)z     wherein M is at least one member selected from the group consisting of thallium and silver; 0.005≦x≦0.35, y is greater than zero and less than 0.1, and 0.7≦z≦1.9 and wherein M is present in an amount sufficient to effect a brightness that is greater than that of the phosphor absent M; said phosphor emitting ultraviolet rays having a wavelength ranging between 280 to 330 nm when excited by ultraviolet rays having a wavelength of 254 nm, and exhibiting a line spectrum corresponding to a wavelength approximating 312 nm.   
     
     
       2. A gadolinium-activated phosphate phosphor according to claim 1, wherein x is not less than 0.05 nor greater than 0.2. 
     
     
       3. A gadolinium-activated phosphate phosphor according to claim 1, wherein z is not less than 0.8, nor greater than 1.3. 
     
     
       4. A gadolinium-activated phosphate phosphor according to claim 1 wherein M is thallium.